ANN ARBOR, MICHIGAN—In a new genetic study of 2,500 people from around the world, biologists from the University of Michigan and Tufts University have found nineteen new pieces of DNA left in the genetic code by viruses that infected human ancestors hundreds of thousands of years ago. According to a University of Michigan press release, the team even found one stretch of DNA in about 50 of the people studied that contains the full genetic code for an entire virus, which might give scientists the tools to study an ancient viral epidemic. “These are remnants of ancient events that have not been fixed in the population as a whole, but rather happened in the ancestors of some people alive today,” said University of Michigan geneticist Jeffrey Kidd. To read more about ancient genetic studies, go to “Denisovan DNA.”